1. Field of the Invention
The present invention relates to a liquid-phase growth process and a liquid-phase growth apparatus for growing a crystal. More particularly, the present invention relates to a liquid-phase growth process and a liquid-phase growth apparatus for continuously growing a crystal film on a plurality of substrates from a solution comprising a crystallizing material dissolved in a solvent comprising a metal or the like in a supersaturated state.
2. Related Background Art
There is known a liquid-phase growth process by way of so-called dipping for forming a crystal thin film on a substrate, where said crystal thin film is formed on both surfaces of said substrate. In general, only the crystal thin film formed on one surface of the substrate is subjected to practical use and because of this, the crystal thin film formed on the other surface of the substrate is wasted.
In order to eliminate this disadvantage, there have been made various proposals which enable formation of a crystal thin film only on one surface of a substrate.
For instance, Japanese Laid-open Utility Model Publication No. 55(1980)-111970 (hereinafter referred to as “Document 1”) discloses a method for growing a crystal film on the front face of a wafer as a substrate by dipping said wafer in a high temperature growth melt, wherein said wafer is dipped in the melt while being held on a wafer holder provided with a platinum plate which contacts substantially over the entire back face of said wafer on which no crystal film is grown. It is understood that the platinum plate in this case serves to prevent the back face of the wafer from being contacted with the melt so that only the front face of the wafer on which the crystal film is grown is contacted with the melt.
Japanese Laid-open Patent Publication No. 57(1982)-76822 (hereinafter referred to as “Document 2”) discloses a liquid-phase epitaxial growth process wherein a substrate holder having four arms arranged at an equal interval and which is held by a retaining bar capable of being moved in either an upward direction or a downward direction is used, where a substrate is arranged in the substrate holder such that it is maintained by said arms of said substrate holder so as be movable in either an upward direction or a downward direction, said retaining bar is moved downward to get said arms having said substrate maintained thereon in a melt so that said substrate is kept afloat on the surface of the melt, whereby a crystal thin film is grown only on the face of said substrate which is contacted with the melt.
However, any of the techniques disclosed in Documents 1 and 2 still has disadvantages which are necessary to be overcome.
Particularly, the technique disclosed in Document 1 has shortcomings such that it takes a time to accurately arrange the substrate (the wafer) in the apparatus (the jig), it is difficult to make such that the melt is completely prevented from being invaded between the substrate and the platinum plate for preventing the crystal growth on the back face of the substrate, and this situation makes it difficult to obtain a product at a high yield and at a reasonable production cost. Besides, the technique disclosed in Document 1 has other disadvantages such that in order to continuously grow a crystal film on a plurality of substrates, the apparatus used is necessary to be designed to be suitable to do so, where the structure of the apparatus becomes to be unavoidably complicated, and there are such shortcomings as above described also in this case.
The technique disclosed in Document 2 has an advantage in that the back face of the substrate is effectively prevented from having the growth of the crystal film thereon. However, the technique disclosed in Document 2 has disadvantages such that when it is intended to load a plurality of substrates in the apparatus at the same time, the apparatus is necessary to be designed to be suitable to do so, where the structure of the apparatus becomes to be unavoidably complicated, and in this case, it takes a certain period of time in order to accurately arrange the plurality of substrates in the apparatus, and this situation makes it difficult to attain satisfactory productivity.